Binaural pick-up cartridge



April 13, 1965 M. DE VRlES BINAURAL rICK-UP CARTRIDGE Filed jAug. 28, 1958 IN VEN TOR.

Mdduel De Un'e 5 BY United States Patent 3,178,520 BINAURAL PICK-UP CARTRIDGE Machiel de Vries, Amsterdam, Netherlands, assignor to Ronette Piezo Electrische Industrie, N.V., Amsterdam, Netherlands, a corporation of the Netherlands Filed Aug. 28, 1958, Ser. No. 757,745 Claims priority, application Netherlands, Oct. 29, 1957, 221,984 7 Claims. (Cl. 179100.41)

This invention relates to a pick-up element comprising two transforming elements for converting mechanical into electrical vibrations, which transforming elements are each connected by means of a coupling member with common stylus holder carrying a stylus, a first portion of the one coup-ling member connected with the stylus holder enclosing at least substantially a right angle with a corresponding first portion of the other coupling memher.

A pick-up element of this type is adapted to be used for tracking records, more particularly gramophone records into which tracks provided with a double sound recording are cut. The groove of such a gramophone record has two walls enclosing an angle of about 90 with each other. Into each of said walls a sound track is cut, which sound tracks are tracked by a needle or stylus. Seeing that the needle or stylus in tracking the tracks will perform movements in two directions that are normal to each other, it is possible to split up said movements of the needle and to transfer them to separate reproducing means. The sound taken up by a separate microphone may be recorded in each of the tracks, the two microphones being arranged in spaced relationship, so that in this manner a stereopho-nical recording and reproduction of the sound can be effected. A difiiculty encountered in arrangements of this type is that the movements of the needle which are normal to each other must be fully separated from each other if the desired effect is to be reached. Another diificulty resides in the circumstance that a pick-up element of the type in question is to be provided with two transforming elements, eg piezoelectrical elements, so that the pick-up element will become rather large and heavy.

The object of the invention is to provide a construction which entirely eliminates these two difficulties.

To this end the pick-up element according to the invention is so constructed that of the first coupling member portions the one ends are connected with each other and the other ends each with a second coupling member portion which is at least substantially normal relative to the associated first coupling member portion, the respective coupling member portions being so shaped and being made of such material that upon moving they-hinge relative to each other.

According to another feature of the invention the pickup element may be so constructed that the one ends of the first coupling member portions are interconnected by an intermediate piece against which the stylus holder bears.

According to a further feature of the invention the coupling members and the intermediate piece may consist of one piece of relatively soft resilient material hav- 3,178,520 Patented Apr. 13, 1965 ing a relatively large internal damping, such as polyvinyl chloride.

According to still another feature of the invention the piece of resilient material may have a smaller cross section adjacent the connections of the coupling member portions with each other and with the intermediate piece respectively.

A pick-up element in which the transforming elements consist of piezoelectrical elements having at least their one ends clamped in a casing, may be so constructed according to the invention that a sleeve is located about the free end of each piezoelectrical element, the associated second coupling member portion whose cross-sectional area increases in the direction towards the sleeve, is secured to said sleeve adjacent the longitudinal axis of symmetry of the piezoelectrical element, the arrangement being such that the movements of all of the coupling member portions and the intermediate piece can only take place in a plane normal to said longitudinal axis.

According to the invention the two piezoelectrical elements may have their main faces located parallel to each other.

Furthermore it is possible according to the invention for the main faces of the two piezoelectrical elements to be co-planar.

Finally it is possible according to the invention to so construct the pick-up element that the two piezoelectrical elements bear against and are separated by an intermediate metal wall which tor both elements forms a terminal electrode.

The invention will be illustrated with reference to the accompanying drawing, showing an embodiment of the pick-up element according to the invention.

FIGURE 1 is a side view of the pick-up element, one half of the casing accommodating the element being removed;

FIGURE 2 is a different elevation of the casing containing the pick-up element according to the invention;

FIGURE 3 is a cross-sectional view and an elevation resp. on line IHIII in FIGURE 2;

FIGURE 4 schematically shows the movements of the stylus and of the coupling members cooperating with the stylus;

FIGURE 5 schematically shows an arrangement in which the crystal elements are co-plana-r, the vibrations to be transmitted by the stylus being located in a horizontal and in a vertical plane respectively.

The pick-up element is enclosed in a casing comprising two halves 1 and 2 preferably made from moulded material. Two piezoelectrical elements 3 and 4 are clamped in the casing 1, 2 with the interposition of a resilient band. Said resilient band meant for interposition between the casing and the element 3 is designated by the numeral 5 (what is said about the construction and manner of seeming the element 3 naturally likewise applies to the construction and manner of securing the element 4). Furthermore the element 3 is supported by a second band of relatively soft material 6. Between the elements 3 and 4 a metal partition wall 7 is located which wall also serves as a common current carrying member for the two elements 3 and 4 and which for said purpose is provided with a terminal 8. Similar terminals 9 and 10 lead to the respective other poles of the elements 3 and 4. Due to this common wall, 7, functioning as an electrode the possibility of wrongly connecting the one element relative to the polarity of the other element is excluded. A stylus holder 11 provided with a stylus 12 is secured to the casing 1, 2. The stylus holder 11 substantially comprises a narrow and thin flexible strip, a portion of which is turned through 90". Between the stylus holder 11 and the casing 1, 2 there is a block of resilient material 14 for supporting the stylus holder 11. Due to this construction the free end of the stylus holder 11 is very readily movable in all transverse directions. The stylus holder 11 bears with a portion located very closely adjacent the stylus 12 against a coupling member 15.

For said purpose the stylus holder 11 is provided with two lugs 16 and 17 which lightly clamp about a projecting portion 18 of said coupling member 15. The coupling member is made from a relatively soft resilient synthetic material, such as polyvinyl chloride, having a large internal damping. The coupling member 15 consisting of one piece comprises two sleeves 19, 20 surrounding the free ends of the elements 3 and 4, four arms 21, 22, 23 and 24 and an intermediate piece 25 connecting the arms 22 and 24 and also carrying the projection 18. As appears from the drawing the arms 22 and 24 as well as the intermediate piece 25 are provided with stiffening ribs 26, 27 and 28 having their largest width in the middle. Owing to this construction as well as owing to the nature of the material the coupling member 15 is more flexible in certain places than elsewhere i.e. in those places where one of the said arms passes into another arm, which places are designated by the numerals 33 and 34 or where an arm passes into the intermediate piece 25, as designated by the numerals 35 and 36. The arms 21 and 23 broaden in the direction towards the sleeves 20 and 19, which has for its result that the connection at 37 and 38 between said arms and said sleeves is relatively stilt, so that movements of said arms in a plane normal to the longitudinal axes of the piezoelcctrical elements 3 and 4 result in a twisting of said elements about their longitudinal axes. It should be noted that the places 37 and 38 where the arms 21 and 23 are connected with the sleeves 19 and 20 are centered relative to said longitudinal axes.

FIGURE 4 diagrammatically shows in what manner the coupling member 15 behaves under the influence of movements according to the arrows designated by 29 and 30. In this figure the inoperative position of the coupling member 15 is shown in a full line, the deflections of the coup-ling member as a result of the movements according to the arrows 29 and being shown in dashes and in dots and dashes respectively. It is of importance for the various arms 21, 22, 23 and 24 to enclose at least substantially right angles while as observed before the coupling member 15 is very flexible in its corners 33, 35, 36 and 34. In said corners a hinging action will take place therefore, which clearly appears from FIGURE 4. During movements according to the arrow 29, for example, the arm 22 which is loaded in longitudinal direction will cause the arm 21 to rotate about the point 37, which results in a twisting of the element 4. The arm 24, on the other hand, will hinge at 34 relative to the arm 23, so that the arm 23 will not transmit a torsional force to the element 3. During movements according to the arrow 39, conversely, only the element 3 and not the element 4 will be twisted. The fact that the junctions and 36 between the intermediate piece 25 and the arms 22 and 24 respectively are also thin is due to the circumstance that the angle between said three portions of the coupling member 15 must admit of varying when movements according to the arrows 29 and 30 take place, which may also be seen from FIGURE 4.

Because the entire coupling member 15 consists of one piece both the manufacture as well as the mounting of said member is extraordinarily simple. Due to this coupling member there is a relatively great freedom in the selection of the position of the main faces of the elements 3 and 4 relative to each other. Without such a construction said faces must necessarily be arranged at right angles to each other and the transforming elements would occupy a large space then, which would result in the pickup element becoming very broad. In the construction according to the invention said faces may be parallel to each other and the elements may be arranged in close proximity.

I would still observe that the casing 1, 2 is provided with portions 31 and 32 projecting therefrom and from the pick-up head, which projections form grips for the pick-up.

The pick-up described hereinbefore is meant for use with a groove the two'side walls of which each enclose an angle of about 45 with the horizontal plane. It will be clear that also other embodiments are possible, notably those in which one of the two directions of vibration that are normal to each other is substantially verticaland the other substantially horizontal. Such an embodiment is shown in diagrammatic FIGURE 5. In this case the point of the stylus transmits vibrations according to the two directions indicated by arrows 29 and 30'. This figure at the same time shows the possibility of the two crystal elements being not parallel, but co-planar.

I claim:

1. In a binaural pick-up for a V-shaped record groove having two distinct groove modulations along the respective two sides thereof, support means, two transducer means each comprising an elongated flat strip of piezoelectric material, one end of said strips being held by said support means, the other end of the strips being wholly unsupported, stylus means connected to said support means for engaging said groove, said strips being mounted in side-by-side arrangement above said stylus means, and integrally molded resilient coupling means supported by the other ends of said strips for operative engagement with said stylus means, said coupling means being integrally molded of resilient material and including first and second pairs of elongated arm portions and two sleeve portions, said arms being arranged generally in the form of a rectangle, said sleeve portions each encircling a respective unsupported end of one of said transducer means, each of said first pair of arm portions being disposed in a direction normal to a respective plane of said groove modulations and being connected with each other at their one ends and in driven engagement with said stylus means, each of said second pair of arms being disposed substantially at right angles to a respective one of said first pair of arms and having their one ends connected with a respective other end of one of the first pair of arms, the other end of each of said second pair of arms being connected with a respective one of said sleeves at a location centered with respect to the longitudinal axis of a respective transducer means.

2. The invention as defined in claim 1, wherein said flat strips of piezoelectric material are disposed with their principal faces in parallel relationship.

3. The invention as defined in claim 1, wherein said integral coupling means comprises polyvinylchloride.

4. The invention as defined in claim 1, wherein said pick-up includes a metal element positioned between said flat strips of piezoelectric material at their one ends in abutting relationship to each strip to provide a common electrical contact.

5. The invention as defined in claim 1, wherein said integral coupling means is of reduced cross-section at the locations where said pairs of arms are connected with each other and with the stylus means.

6. The invention as defined in claim 1, wherein said integrally molded coupling means includes an intermediate portion, said first pair of arms being connected with each other by the intermediate portion.

7. The invention as defined in claim 6, wherein said 5 6 stylus means is connected with said first pair of arms by 2,934,610 4/60 Dieter 179--100.41 said intermediate portion. 3,055,989 9/62 Bachman et a1 179-100.41

References Cited by the Examiner FOREIGN PATENTS UNITED STATES PATENTS 5 686,777 1/53 Great Britain.

1,520,357 12/24 Lord. OTHER REFERENCES 2,093,540 9/37 Blurnlein 179100.41

2,114,471 4/38 Keller. 1313211t9s5c1. German printed apphcation T11092, Dec.

2,328,478 8/43 Mason 179100.41

2,328,952 9/43 Burt 179-10041 IRVING L. SRAGOW, Primary Examiner.

2,775,460 12/56 Shivack.

2 25 7 3 3 /5 De Vries 179 1 0 41 NEWTON N. LOVEWELL, STEPHEN W- CAPELLI,

2 35 3 3 1 5 Hgumanny L. M. ANDRUS, Examiners, 

1. IN A BINAURAL PICK-UP FOR A V-SHAPED RECORD GROOVE HAVING TWO DISTINCT GROOVE MODULATIONS ALONG THE RESPECTIVE TWO SIDES THEREOF, SUPPORT MEANS, TWO TRANDUCER MEANS EACH COMPRISING AN ELONGATED FLAT STRIP OF PIEZOELECTRIC MATERIAL, ONE END OF SAID STRIPS BEING HELD BY SAID SUPPORT MEANS, THE OTHER END OF THE STRIPS BEING WHOLLY UNSUPPORTED, STYLUS MEANS CONNECTED TO SAID SUPPORT MEANS FOR ENGAGING SAID GROOVE, SAID STRIPS BEING MOUNTED IN SIDE-BY-SIDE ARRANGEMENT ABOVE SAID STYLUS MEANS, AND INTEGRALLY MOLDED RESILIENT COUPLING MEANS SUPPORTED BY THE OTHER ENDS OF SAID STRIPS FOR OPERATIVE ENGAGEMENT WITH SAID STYLUS MEANS, SAID COUPLING MEANS BEING INTEGRALLY MOLDED OF RESILIENT MATERIAL AND INCLUDING FIRST AND SECOND PAIRS OF ELONGATED ARM PORTIONS AND TWO SLEEVE PORTIONS, SAID ARM BEING ARRANGED GENERALLY IN THE FROM OF A RECTANGLE, SAID SLEEVE PORTIONS EACH ENCIRCLING A RESPECT UNSUPPORTED END OF ONE OF SAID TRANSDUCER MEANS, EACH OF SAID FIRST PAIR OF ARM PORTIONS BEING DIS- 